Brine Management
| Issues - Brine Management | |
|---|---|
| Search MemRe for Brine Management | |
| NCEDA projects relating to brine management | |
The growing demand for water is partially met by desalination plants. These plants continue the trend of using membrane technologies (especially RO) to produce purified water. Operating with recoveries from 35% to 85% RO plants generate huge volumes of concentrates. If these salt streams are not properly managed they may adversely impact the environment. [1] As such, brine management represents the most pressing challenge of all desalination technologies. Potential treatments to overcome the environmental problems associated with direct discharge of the concentrates may be classified by the feedwater source.
Concentrates from coastal plants may be disposed of by direct discharge. Toxilogical investigations, laboratory-based experiments, and manipulative field experiments show the potential for brines and their constituents to illicit adverse impacts on aquatic organisms when present at sufficient concentrations. Concentrates produced from thermal desalination are generally hotter than the surrounding water, causing further ecological damage. [2] Metals (copper, nickel, iron, chromium, zinc, etc.) from thermal corrosion may also be discharged. Additionally, a variety of chemical agents are added during pre and post treatment to: enhance flocculation, prevent foaming, and reduce membrane deterioration. These agents produce further biological effects. The most pronounced effects on waters are eutrophiction, pH variations, accumulation of heavy metals, and the sterilizing properties of disinfectants. As a result of these effects, direct disposal of RO concentrates to seawater is on the decline.
Traditionally, options for disposal of the concentrates from inland desalination plants have been deep well injection and surface water discharge, or concentration of brines in evaporation ponds. While evaporation ponds are simple, they come at a significant capital cost as they are required to be lined by state environmental protection agencies. Inland plants have no possibility of discharging their concentrate into the sea, so the development of other management options is a high priority.
References
- ↑ Pérez-González, Antia, et al. "State of the art and review on the treatment technologies of water reverse osmosis concentrates." Water Research 46.2 (2012): 267-283.
- ↑ Roberts, David A., Emma L. Johnston, and Nathan A. Knott. "Impacts of desalination plant discharges on the marine environment: A critical review of published studies." Water Research 44.18 (2010): 5117-5128.